Pneumatic tool.



Patented Apr. I6, 190|.

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T. BARVRow. PNEUMATIC TOOL.

\App1ics.tion flled June 6, 1899.)

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WITNESSES.

(No Model.)

anni Ormea,

THOMAS BARROIV, OF CLEVELAND, OHIO, ASSIGNOR TO THE CHISHOLM AND MOOREMANUFACTURING COMPANY, OF SAME PLACE.

Pneumatic Toor..

SPECIFICATION forming part of Letters Patent No. 672,306, dated April16, 1901.

Application led June 6, 1899. Serial No. 719,563. (No model.)

To all whom, t may concern:

Be it known that I, THOMAS BARROW, a citizen of the UnitedStates,residing at Cleveland, in the county of Cuyahoga and State ofOhio, have invented certain new and useful Improvements in PneumaticTools; and I do declare the following to be a full, clear, and eX- actdescription of the invention, such as will enable others skilled in theart to which it appertains to make and use the same, reference being hadto the accompanying drawings, and to the letters and figures ofreference marked thereon, which form a part of this specification.

This invention relates to that class of tools in which compressed air orother pressure medium acts upon a piston to cause it to deliver blows inrapid succession to a cutting, calking, riveting, or chipping tool.

The object of this invention is to produce a cheap, simple, yet veryefficient tool of this character in which the various parts are soarranged as to secure the greatest amount of working energy, while atthe same time reducing the shock of the return blow of the piston to aminimum; and with these objects in view my invention consists of theparts and combination of parts,as willbe more fully hereinafter pointedout.

In the drawings, Figure l is arverticallongitudinal section of myimproved tool with the piston in its upper position. Fig-2 is a similarview showing the piston in its striking position, resting against thebit of the tool. Fig. 3 is a vertical cross-section on the line or: no,Fig. l.

A represents the barrel of my improved tool, C the exterior' covering oriinish, and D the handle thereof. The ends of the barrel are providedwith interior screw-threads by means of which the handle C is secured inone end of the barrel, while the tool-holder D is secured in theotherend.

lis a valve-box, of cast-iron, steel, or brass, turned andmade a drivingfit in the barrel and provided with ports corresponding with ports inthe barrel, to be hereinafter referred to.

. 2 is a port formed in the barrel A on one side, one end of which opensinto the barrel below the uppermost position of the hammer, while theother end opens into the valve-box.

et is a port extending through the outside covering or jacket and thebarrel.

3 is a port formed in and through the barrel, through which theexhaust-air may pass from the top of the valve down between the barreland the cover or jacketB and out through the port 4. v

5 is an inlet for the air or other pressure formed in the handle C, and6 is another port formed in the barrel immediately underneath the coveror jacket B, said port opening at one end into the lowermost part of thebarrel, while the other end opens into the valve-box l. The valve-boxhas a central bore in which the valve 7 reciprocates, said valvecomprising two piston-heads 8 and two sliding valves 9, and l0 is ascrew-threaded plug secured in the top of the central bore of thevalve-box.

1l is a port or air-passage formed in the valve-box,registering at oneend with the airinlet 5 in the handle C.

l2 and 13 are openings cut through the upper wall of the port ll,leading into the valvebore of the box.

14 and l5 are two ports cut through the top of the valve-box andseparated by means of the partition 16. The barrel A has ports similarto and registering with the ports 14 and l5, separated by a partitionregistering with and forming a continuation of the partition I6,said`ports all leading into the port or passage 6 between the jacket andthe barrel.

17 and 18 are openings or ports opening in to the valve-bore, the portI7 providing for the exhaust-air from the bottom of the ham mer, the airpassing up between the barrel and jacket and out through the portoutside of the jacket, the port 17 providing for the eX- haust from thetop of the hammer.

2O is a port formed in the valve-box, one end opening into thevalve-bore, while the other end opens into the barrel.

2l is a port at the bottom of the valve-bore, registering with the upperend of the port or passage 2.

22 is a collar having a central opening and 5 This collar, with thevalve-box, forms a chamber 24, which is connected with the port 11 bymeans of a comparatively small port 25, formed to one side of the port11,` as shown in Fig. 3, thus running back of the port 2.

26 is a piston or buffer having an annular head adapted to work in thechamber 24,while the stem of the piston works in the annular opening inthe collar 22.

27 is the hammer, provided with peripheral groove 28. y

29 is aport through the barrel A.

The parts being positioned as shown in Fig. 1, air is admitted throughthe handle into the port 1l, from which it passes through port 13 intoport 2O and thence into the barrel A on top of the hammer 27, therebyforcing the hammer down to givel a blow to the tool 30, the air in frontof the hammer in the barrel being forced into the lower end of the port6, from which it escapes through the port 16, through the valve-opening17 outside the tool. As soon as the upper edge of the hammer passes orclears the port 3 in the barrel the air-pressure on top of the hammerrushes into said port and passes up the port to an opening in the plug10, through which it escapes into the valve-bore, (in the valve-box infront of the piston 8 of the valve,) thereby forcing the valve down andmoving the slide 9 over the port 17, thereby closing it, at the sametime opening the ports 12 and 14, thus permitting the compressed air topass through the ports 12 and 14 into the port or passage 1G to thebottom of the barrel A under the hammer 27, thus throwing the hammerupward to its original position. When the hammer is forced downward, acertain amount of air escapes from the barrel through the port 2 intothe valve-bore back of the piston 8a. As soon as the valve is forcedback to open the ports 12 and 14 the air in front of piston 8a escapesthrough port 2 into the upper annular groove 28 of the hammer and passesfrom the tool through the port 29. When the hammer gets high enough, theair passes from the barrel into the port 2, thence intothe valve-boreback of piston 8', thereby forcing or throwing the valve to the positionshown in Fig. 1 and opening the prts 13 and 20 and closing the ports 12and 14 and opening the port 17. In this position the exhaust can escapethrough port 3 into the lower annular groove 28 in the hammer and thenceout through the port 4. The exhaust from the top of the hammer, as it isforced upward, passes through the exhaust 18. When the valve is forcedupward, as sho'wn in Fig. 1, one of the slides 9 closes the port 18,thus closing all avenues of escape for the air when the hammer isdescending until the hammer passes the port 3, when the operationabovedescribed takes place.

The port 25, forming a contracted continuation of port 11 into thechamber 24, is always open, whereby a constant pressure is alwaysexerted within said chamber upon the annular head of the piston `orbuffer 26. Thus when the hammer is forcibly returned to its upperposition it strikes the stem of the buffer, which is thereupon forced inthe chamber 24 against the compressed air, which acts as a cushion andtakes up all concussion, thereby relieving the operator of the jars andshocks incident to this class of tools as heretofore constructed.

It is obvious that I may employ some suitable means to automatically cutoff the motive force when the tool is temporarily out of use.

What I claim, and desire to secure by Letters Patent, is-- 1. In a toolof the character described, the combination with the valve-box, having acentral bore, one end of which is closed, of a valve adapted to slide insaid bore,inlet and discharge ports formed in said box, aflanged collarhaving a central opening and abutting one end of the valve-box therebyforming a chamber, a buffer mounted in said chamber and projectingthrough the central opening and a port formed in said flanged collarcommunicating with the inlet-port.

2. In a tool of the character described the combination with thevalve-box having a central bore, one end of which is closed, of a valveadapted to slide in said bore and comprising two pistol] e heads and twosliding valves, a flanged collar abutting one end of the said boxthereby forming a buffer-chamber, a central opening in said collar,abuffer mounted in said chamber and extending through said centralopening, a port formed in the iange of said collar communicating withthe inlet-port, the port 2 opening into the barrel below the uppermostposition below the hammer and into the valve-box, the ports 3 and 4, theinlet-port 5, and the port 6 one end of which opens into the lowermostpart of the barrel while the otherend opens into the valve-box.

3. In a pneumatic tool, the valve-box comprising the Valve-bore, aconstantly open port reversing and exhaust ports and a buiferchamberconnected with the said open port in combination with a buffer workingin the buffenchamber and a valve comprising a piston at each end and twointermediate slides adapted to register with the reversing and exhaustports.

In testimony whereof I affix my signature in presence of two witnesses.

THOMAS BARROW.

Witnesses:

H. B. PUMPHREY, MYRA 'PANGBURN IOO IIO

